Dalit does not mean low caste.
Dalit does not mean any religion. Dalit refers to some unique people
with distinct culture and traditions.

But how did they lose their identity and their
uniqueness?

"Every hour - two dalits are assaulted,
every day three - dalit women are raped and two dalits are murdered
....two dalit houses are burnt." (Human Rights Education
Movement in India)

A Dalit is not only forbidden
to enter the home of a Brahmin but he must also not draw water from
the same well, not eat from the same pot or place. He must not glance
at or allow his shadow to fall on the Brahmin. All these acts will pollute
the "pure Brahmin."